1. Field of the Invention
The present invention relates to an image-providing apparatus and control method thereof, a printing apparatus and a control method thereof, as well as to a printing system obtained by interconnecting the image-providing apparatus and the printing apparatus.
2. Description of the Related Art
In the past, a personal computer (PC) was necessary when printing image data held in a digital still camera (hereinafter DSC) or another image-providing apparatus using a printer or another printing apparatus. However, in recent years, it has become increasingly common to use the so-called direct printing system (hereinafter “direct printing system”), in which a DSC and a printer are interconnected through a communication interface such as a USB, etc., and image data from the OSC is sent directly to the printer for printing.
Standards related to communication between a DSC and a printer, which are used to implement such a direct printing system, stipulate that image files in JPEG format or TIFF format are to be transferred from the DSC to the printer.
In recent years, there have been implemented printers having features used for automatically correcting image brightness, contrast, white balance, etc., as a result of which it has also become possible to obtain automatically corrected image output simply by outputting image data from a DSC to such a printer.
The image processing features that printers are equipped with include red-eye correction, backlight compensation, noise reduction, etc., and their number tends to grow every year. On the other hand, there appeared DSCs equipped with similar image correction features, as a result of which image data produced by image correction on the DSC side is outputted to printers as well.
In certain situations, captured images are obtained, in which the height of the sea horizon or land horizon, building outlines and other things that are supposed to be horizontal varies (is tilted) at the right and left edges of the images.
The known methods used for modifying such failed images include, for example, a method wherein printing is performed by rotating an image so as to make it horizontal and selecting a cropping operation such that blank regions generated by the rotation are not printed.
In the direct printing system, the crop-and-print feature is implemented by sending the original image, cropping position information, and “bordered/borderless” layout information from the DSC to the printer and performing image processing based on this information on the printer side.
Most automatic image correction processing commonly employs histograms generated from image data and Exif information contained in image files as data used for the adjustment of brightness, contrast, white balance, etc. The problem is that, for this reason, when images that have undergone image correction in the DSC are output to a printer equipped with the automatic image correction feature, the printing results end up being different from cases in which they are output to the printer without image correction in the DSC.
The problem is that when, for example, a cropping area is designated and sent to a printer during a crop-and-print operation, the brightness and contrast do not remain stable because even in case of regions cropped from the same image, the pixel histogram ends up being different depending on the cropping area.
Moreover, when printing images produced by a rotation process (tilt correction) in the DSC, images obtained by rotation are sent to the printer along with cropping information. However, when image processing is performed on the printer side, empty regions produced by rotation, which cannot be interpolated (blank regions), are included therein, which makes it impossible to obtain correct image histograms. Furthermore, because the size of the blank regions varies depending on the amount of rotation, a histogram changes depending on the magnitude of the amount of rotation even when the same image is printed. The problem that occurs as a result is that images automatically corrected by the printer have unstable brightness, contrast and color tint.